Hydraulic device for pumping molten metal and/or controlling a molten metal flow

ABSTRACT

A hydraulic device for pumping molten metal and/or controlling its flow, comprising an enclosure that forms internally a cylindrical chamber, for the connection of at least one first duct and one second duct for the passage of molten metal, within which a piston can slide hermetically in order to pump and/or control flow, an insulating cushion of inert gas being interposed between the piston and the molten metal, the piston being associated with an actuator for moving it with a reciprocating rectilinear motion.

The present invention relates to a hydraulic device for pumping moltenmetal and/or controlling its flow.

BACKGROUND OF THE INVENTION

The invention is particularly suitable for systems for forming metalcastings, in which the molten metal has to be transferred from theholding furnace to the dies substantially with a pouring operationrather than through ducts.

It is known in the art that molten metals are difficult to transferamong the various process systems due to their high temperature,corrosiveness and noxious gas emissions.

SUMMARY OF THE INVENTION

The aim of the present invention is to provide a hydraulic device to beinterposed in ducts for the passage of molten metal that allows to pumpa chosen quantity of metal and/or control the flow of said metal.

Within this aim, an object of the invention is to provide a device thatis suitable for metals of various kinds.

Another object is to provide a device that has a simple structure.

Another object is to provide a device that can be manufactured withknown systems and technologies.

This aim and these and other objects that will become better apparenthereinafter are achieved by a hydraulic device for pumping molten metaland/or controlling flow thereof, characterized in that it comprises anenclosure that forms internally a cylindrical chamber, for theconnection of at least one first and one second duct for the passage ofmolten metal, within which a piston can slide hermetically in order topump and/or control flow, an insulating cushion of inert gas beinginterposed between said piston and the molten metal, said piston beingassociated with piston movement means for actuating movement thereofwith a reciprocating rectilinear motion.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will becomebetter apparent from the description of a preferred but not exclusiveembodiment thereof, illustrated only by way of non-limitative example inthe accompanying drawings, wherein:

FIG. 1 is a view of a device according to the invention for pumpingmolten metal;

FIG. 2 is an enlarged-scale view of a detail of the device of FIG. 1;

FIG. 3 is a view of the device according to the invention forcontrolling the flow of molten metal;

FIG. 4 is a view of a composite apparatus comprising a plurality ofdevices according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the figures, a hydraulic device for pumping moltenmetal according to the invention is generally designated by thereference numeral 10.

The device comprises an enclosure 11, which forms internally acylindrical chamber 12 for the connection of at least one first duct 13and one second duct 14 for the passage of molten metal 15, within whicha piston 16 can slide hermetically.

An insulating cushion 17 of inert gas, suitable to keep the metal 15 andthe piston 16 separate, is interposed between the piston 16 and themolten metal 15.

The piston 16 is associated with means 18 for moving it with areciprocating rectilinear motion, as better described hereinafter.

The piston 16 is constituted by a substantially disk-like portion 19,which can slide hermetically within the cylindrical chamber 12, and by asubstantially cylindrical portion 20 whose diametrical dimension issmaller than the corresponding dimension of the cylindrical chamber 12,in order to form a tubular interspace in which the inert gas is presentso as to form a cup-shaped insulating cushion 17.

The pressure and volume of the gas that forms the insulating cushion 17are controlled by means of an electric valve 21, which controls theinflow of gas into the cylindrical chamber 12 through a radial duct 22formed in the enclosure 11.

The radial duct 22 has an outlet 23 that leads inside the cylindricalchamber 12 and is arranged in a region in which it is always connectedto the insulating cushion 17 even during the movement of the piston 16,which never makes contact with the metal 15.

A gasket 24 for forming a seal with the cylindrical chamber 12 isarranged perimetrically with respect to the disk-like portion 19.

The cylindrical portion 20 is provided with an outer shell 25, which issubstantially cup-shaped and is made of ceramic material; said shell isfilled with insulating putty 26, such as for example the putty knowncommercially by the trade-name INSURAL, and is fixed to the disk-likeportion 19 by way of transverse pins 27.

The enclosure 11 comprises a first portion 28, which normally containsthe metal 15 and is constituted by an inner layer 29 made of ceramicmaterial, by an intermediate layer 30 made of insulating putty, such asfor example the putty known commercially by the trade-name INSURAL, andby an outer layer 31 made of steel; and a second portion 32, which nevercontains metal 15 but inside which the piston 16 can slide; said secondportion is provided with an outer jacket 33 that is suitable to form aninterspace 34 in which a cooling liquid can flow through inlet andoutlet connectors 35 and 36.

The enclosure 11 is to be arranged so that the cylindrical chamber 12has a vertical axis and the first portion 28 is arranged below thesecond portion 32.

The first and second ducts 13 and 14 are connected at a bottom 37 of thefirst portion 28; at least one of said ducts has an intake function andat least one has a delivery function.

The embodiment described above for the enclosure 11 and the piston 16 isparticularly suitable if the molten metal 15 is aluminum, which is ahighly aggressive metal.

In the case instead, for example, of non-aggressive metals or alloys,the piston 16 and the enclosure 11 can be made of stainless steel.

The means for moving the piston 16 are constituted, in this case, by alinear actuator 38 with a body 39 that is fixed above the second portion32 and with a head of the stem 40 that is fixed to the disk-like portion19, on the opposite side with respect to the cylindrical portion 20.

The linear actuator 38 can be of the hydraulic type and can be managedby an electronic control unit for controlling the advancement of thepiston 16 so as to control accordingly, by knowing the geometricparameters, the quantity of pumped or drawn molten metal.

FIG. 3 illustrates a device 110, according to the invention, forcontrolling the flow of molten metal.

The device 110 has a simplified structure with respect to the device 10and comprises an enclosure 111 that forms internally a cylindricalchamber 112, for the connection of a first duct 113 and a second duct114, within which a piston 116 can slide hermetically.

The piston 116 is structurally similar to the piston 16 of the device10, forming a cup-shaped insulating gas cushion 117.

In this case also, the pressure and volume of the gas that constitutesthe insulating cushion 117 are controlled by an electric valve 121 thatcontrols the inflow of the gas through a radial duct 122 with an outlet123 arranged in such a region that it is always in contact with thecushion 117.

The enclosure 111 is constituted by a first portion 128, which isconstituted by an inner layer 129 made of ceramic material, anintermediate layer 130 made of insulating putty, and an outer layer 131made of steel.

The second portion 132 in which the piston 116 can slide is a tubularsteel body.

In this case also, the embodiment shown for the enclosure 111 and thepiston 116 is particularly suitable if the molten metal 15 is aluminum,which is a highly aggressive metal.

As mentioned, the first and second ducts 113 and 114 are connected tothe first portion 128 and are arranged in this case so that theirlongitudinal axes are parallel at different heights.

The piston 116 is associated with a linear actuator 138, which has abody 139 that is fixed above the second portion 132 of the enclosure 111and a head of the stem 140 that is fixed to the disk-like portion 119 ofthe piston 116 on the opposite side with respect to the cylindricalportion 120.

In this case, the linear actuator 138 is of the pneumatically-actuatedtype, since stroke limit control is sufficient to affect the flow of themolten metal 15, blocking said first and second ducts.

Advantageously, it is possible to combine a device 10 for pumping moltenmetal with two devices 110 a and 110 b for controlling the flow of themolten metal as shown in FIG. 4.

In particular, upstream of the first duct 13 there is a first flowcontrol device 110 a, while downstream of the second duct 14 there is asecond flow control device 110 b.

By alternately actuating the closure and opening of the flow controldevices 110 a and 110 b, it is possible to control the intake anddelivery of the pumping device 10 from the first and second ducts 13 and14.

In practice it has been found that the present invention has achievedthe intended aim and objects.

The device according to the invention has a structure which makes itpossible to control the quantity of molten metal pumped into the ducts.

The high temperature of the molten metal would not allow to use minimalplays between the piston and the cylindrical chamber within which itslides.

The inert gas cushion prevents the molten metal from seeping into theclearances between the piston and the cylindrical chamber and hinderingin any way the movement of the piston.

Moreover, the play is such that the structure is not affected by theexpansions of the material caused by the high operating temperatures.

Furthermore, by controlling the pressure and the volume of the gas ofthe cushion by way of the electric valve, it is possible to give thedevice high flexibility with regard to the materials used and to thepressures applied.

The present invention is susceptible of numerous modifications andvariations, all of which are within the scope of the appended claims.

The technical details may be replaced with other technically equivalentelements.

The materials, so long as they are compatible with the contingent use,as well as the dimensions, may be any according to requirements.

The disclosures in Italian Patent Application No. PD2001A000302 fromwhich this application claims priority are incorporated herein byreference.

1. A hydraulic device for pumping molten metal and/or controlling flowthereof, comprising an enclosure that forms internally a cylindricalchamber, for the connection of at least one first duct and one secondduct for the passage of molten metal, within which a piston can slidehermetically in order to pump and/or control flow, an insulating cushionof inert gas being interposed between said piston and the molten metal,said piston being associated with piston movement means for actuatingmovement thereof with a reciprocating rectilinear motion, said pistoncomprising a substantially disk portion, which forms a seal with saidcylindrical chamber, and a substantially cylindrical portion whosediametrical dimension is smaller than that of said cylindrical chamberin order to form an interspace comprising inert gas that forms acup-shaped insulating cushion, said substantially cylindrical portioncomprising an outer shell that is substantially cup-shaped, is made ofceramic material, is filled with insulating putty, and is fixed to saidsubstantially disk portion.
 2. The device of claim 1, wherein saidsubstantially cylindrical portion is fixed to said substantially diskportion by way of transverse pins.
 3. A hydraulic device for pumpingmolten metal and/or controlling flow thereof, comprising an enclosurethat forms internally a cylindrical chamber, for the connection of atleast one first duct and one second duct for the passage of moltenmetal, within which a piston can slide hermetically in order to pumpand/or control flow, an insulating cushion of inert gas being interposedbetween said piston and the molten metal, said piston being associatedwith piston movement means for actuating movement thereof with areciprocating rectilinear motion, said enclosure comprising a firstportion within which the molten metal is normally present, said portionbeing constituted by an inner layer made of ceramic material, anintermediate layer made of insulating putty, and an outer layer made ofsteel.
 4. The device of claim 3, wherein said enclosure comprises asecond portion, within which said piston slides, said second portionbeing provided with an outer jacket that forms an interspace in which acooling liquid flows.